It is a well known practice in the electric motor manufacturing industry to coat and impregnate work pieces, such as armatures and stators, with a resin. Traditionally, this process has been implemented through the use of long, conveyor-driver ovens in which a plurality of work piece fixtures are mounted onto parallel chains. The work pieces are loaded onto a work piece fixture and are transported, in an indexed fashion, through the phases of preheat, trickle, gel and cure. These processes are completed while the work piece is continuously rotated by the work piece fixtures. The work piece fixtures are rotated by a separate system of rotation chains that engage sprockets on the work piece fixtures.
There are numerous problems associated with the above-described linear coating and curing process. The machines required to carry out this process are very long, ranging from twelve to thirty feet or more, and require large amounts of floor space. Additionally, there are several stations along the conveyer line where it is desirable to precisely locate the position of the armatures or stators because precise operations must be carried out. For example, the load/unload point, and the four to six stations where the resin is applied to the work piece, must be accurately located. On a conventional chain-driven machine, it is possible to roughly locate only a single work piece at the load/unload point, and the resin application stations remain essentially unlocated. The chain that conveys the work piece fixtures is simply not precise enough to produce predictable or repeatable work piece locations. Aggravating this situation is the fact that as the drive chains heat up during a normal production day, the fixture locations change as the chains expand and stretch from wear and lack of lubrication.
In many cases it is desirable to have the armatures or stators rotate at different speeds at different stages of the process. In current machines a multitude of chain driven rotation drives are utilized. As the work piece indexes from one drive chain to the next, the fixture sprockets are forced to find their own mesh with the rotation chains. As a result, it is quite common to hear loud crashes within the oven as a sprocket tooth collides with the roller on a rotation chain. This collision causes damage to both the drive sprockets and the rotation chains, and also places strain on the fixture carrying chains and the fixture bearings. It is also desirable to avoid the creation of areas between the separate sections of the drive chains where the work pieces do not rotate, which can causes uneven balance of the resin on the work piece.
Accordingly, there exists a need for an oven for applying and carrying resin which is compact, is able to precisely locate the work pieces, can rotate the work pieces at different speeds, and is easy to service and maintain.